sweitzerworks

Hey gang!
I've got an 87 4x4 with around 140k miles on it and I'm interested it how I can improve my mileage.

I've removed all the emissions except for the charcoal canister and the cat and have made the following improvements (relevant to fuel economy):

Weber 32/36 w/ LCE Spiral Adapter
LCE Header and 2.25" Pro-Flow exhaust
LCE Pro dist. cap and rotor
NGK Plugs/Wires

I did all this around 25k miles ago (along with LCE Pro clutch, head gasket, water/oil pump and timing chain) after which I was getting around 22mpg. About a year and 25k later, with no other modifications, I'm getting more like 17-18mpg! Any ideas on what happened or what I can do to improve this?

Please let me know, I'm sure there's a number of folks here with similar setups.
Thanks!
Jackson

L5wolvesf

Do you drive it hard or otherwise?
Did you do any tuning of the Weber?

Co_94_PU

iTrader: (-1)

Time for a tune up, maybe a little ahead of schedule but not out of line really. There is also winter fuel mixture, the stabilizer and anti wetting agent stuff displaces gasoline in the mix. Add in higher humidity, which the ethanol will suck right up displacing more gasoline as well as dilute the ethanol. Probably some other stuff I'm overlooking in the fuel mix..

And you've likely altered your driving patterns a bit from when you were doing the initial calculation. It really doesn't take much more acceleration per a given distance to alter the MPG.

wyoming9

iTrader: (1)

Done any house cleaning lately I find things tend to stay in the truck and not get taken out

I can easily remove a 1000 pounds just removing un needed things

If you have been fighting head or cross winds that really knocks down the mileage

I don`t worry to much as long as the numbers are in MPG when they drop into GPM I look at things

flg8r22

iTrader: (1)

Are you in California or another state with inspections? I removed the cat on an 86 that I had with under 200k it was very restricted and the power loss led to me driving it harder thus poorer fuel mileage. Took the cat out and it was like driving a newer truck. Tony

sweitzerworks

I'm in Portland Oregon at the moment (sea level).

I've never jetted the carb, just the find tuning when I first installed it and then again about 6k after that.

My last mileage check was a 4 hour drive @ around 65mph on %90 highway with no wind.

I'm an extremely economic driver and use neutral frequently, so user error is unlikely.

Since installing the LCE header and 2.25" exhaust, the airflow feels anything but restrictive. I think the high-flow cat is doing it's job well.

As far as tuning the Webber, I wouldn't be sure where to start.

I may try pulling/replacing the plugs and see how they look.

flg8r22

iTrader: (1)

Sorry I misread. I understood that you still had the factory cat. Good luck diagnosing. Tony

sweitzerworks

No problem. To tell you the truth I've always been curious how she'd run without it. Do you just end it there or continue it through to the muffler?

flg8r22

iTrader: (1)

I still ran a muffler (a cheapo). I think the truck lost a hundred pounds losing that factory cat.

L5wolvesf

There are posts here regarding tuning the Weber. When you change other components on the engine, like a header, retuning the carb is a very good idea - for mileage and performance.

atcfixer

iTrader: (1)

Not sure if the weber or asin would be better mpg, but carb/tuning there will be a huge factor... in fact I think EFI gets more power and MPG, maybe a conversion is in order?

Here are a few things I'd do if I didn't care about off roading...

If you don't have manual locking hubs, get a pair on it.
Check what gear ratio the axles are, if it's 4.56, get some 4.10s, or try to source 3.91s... if you NEVER use 4x4, you could swap out to a 2wd gear ratio like 3.53 or 3.42.
If it's an automatic, swap to a manual (replace truck might be cheapest option), newer autos do quite well, the older hydrolic based shifted ones are bad mpg eaters.
Lower the body ride height (adjust torsion bars to be lower / softer ride)
if you don't regear axles, you could also look at running oversized tires, 31-32in generally fits w\o mods, or very slight mods.
Run high quality fluids, full synthetic is ideal, redline makes good fluid but expensive for the trans/diffs.
Run max sidewall pressure on your tires, generally 35 or 44psi unless you have a higher load rating then they hit 60-100psi depending on just how high the load rating goes. Generally tires will wear better if alignment is good, will be less rolling resistance, but will give a harsher ride. I have load range E on my Tacoma, so it's at 80psi, my corolla is 44psi max so I run it around 45-50psi.
Reducing weight helps, but it isn't a huge % increase unless you don't drive very eco friendly....
talking about that, #1 factor is the driver, read up on how your driving habits can be changed for better mpg. Some are legal, some might not be (some states might be illegal to coast in neural which is stupid in my opinion.)

To go extreme, power steering delete, AC delete, some people even do alt delete and recharge their battery at home and replace the factory style battery with a deep cycle. You could go crazy for lighter rims, tires etc but it is a truck, so they typically get used, if not get a car, you'd be way ahead at base line.


General rule of thumb is reduce weight, resistance (power steering etc), gear the highest you can within reason, and drive at slower speeds (generally 35-45mph is highest mpg, some domestics are 50-55ish depending on engine/trans design). I can hit instant mpg 30+ with my SR5 T100 4x4 extended cab 5 speed at 35mph with slightly over sized tires @ around 32inch and ~40psi (35psi max sidewall soft winter tires).

Instant feedback really helps encourage good driving (eco wise) habits, however carbs can't give you an exact mpg figure, the closest thing would be a vacuum gauge. High vacuum = best mpg, low vacuum = bad mpg. If the truck was converted to EFI, there is a gauge out there you could wire up to monitor a few sensors and give instant mpg results, or a newer engine/ecu could give OBD2 which has tons of cheap mpg gauges as options.

Oh to give a sort of apples to apples comparison, My 86 2wd long box 22R 5 speed pickup got around 25-30mpg depending if loaded or not etc. that's with a front caliper dragging and the carb float level too high (flooding while braking and too rich at idle) so idle was adjusted up ~1500 rpm. I put larger tires from a jeep on it mainly because the tires were shot on it and it had 3.53 ratio rear end. I'd have to ride the clutch from a stop to around 10mph and generally drove around in 5th gear around 45-50mph based on GPS. MPG calc was adjusted based on the speed difference %. If I had unlimited time/funds, I'd drop in a 2.7L from a Tacoma/T100 in it and get the higher rear end from a 4 speed truck (something like 3.21) and of course swap out the trans with the engine, it came with a W55 so high first gear vs W56. I probably wouldn't change the mpg much, but the power and instant feedback would be awesome.